Manufacturing method for a facing having a two-layered structure

ABSTRACT

A manufacturing process for a two-layered facing  1  includes: a front material preparation step  11 ; a backing material preparation step  21 ; and a molding step  31 . The backing material preparation step  21  includes the following steps: a papermaking step  22  in which short fibers and pulp material are blended and made into a paper, the paper is then coated with a binding agent and dried to obtain a paper sheet  4 ; and a winding step  23  in which the paper sheet  4  is cut into a tape-like form and rolled into a ring shape to obtain a backing molding material  5 . In the molding step  31 , the two-layered facing  1  is manufactured by laminating together a front material  2  manufactured in front material preparation step  11  and the backing molding material  5  manufactured in backing material preparation step  21  and thermally molding the two materials together while applying pressure.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a manufacturing method for a facing. More specifically, the present invention relates to a manufacturing method for a facing having a two-layered structure.

[0003] 2. Background Information

[0004] Automotive clutches use a clutch disc that intermittently engages with a flywheel and transfers power by means of friction. A conventional clutch disc has, for example, two annular friction facings and a cushioning plate disposed therebetween. Known structures for the annular friction facings include a two-layered structure having a front material and a backing material. The front material serves as a friction surface and the backing material serves to support and reinforce the front material. In conventional structures, the front and backing materials are integrally molded together. The backing material conventionally used in this kind of friction facing is made of a material such as a light alloy or glass mat that has been punched into a ring shape. When the backing material is manufactured by punching, the yield of the light alloy or glass mat material is relatively poor because punching inherently ensures that material is removed, and, hence, wasted.

[0005] In view of the above, there exists a need for a manufacturing method for a facing having a two-layered structure that overcomes the aforementioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.

SUMMARY OF THE INVENTION

[0006] An object of the present invention is to improve the yield of the material used to make the backing material in a manufacturing method for a facing having a two-layered structure.

[0007] In accordance with a first aspect of the present invention, a manufacturing method for a backing molding material that is molded integrally with a front material having a friction surface in a two-layered facing is provided. The method includes the following steps:

[0008] A papermaking step in which a paper sheet is obtained by blending short fibers and pulp material and making them into paper, coating the paper with a binding agent, and drying the same

[0009] A winding step in which a backing molding material is obtained by cutting the aforementioned paper sheet into a tape-like form and winding it into a ring shape

[0010] With this manufacturing method, the material used to make the backing material is not wasted as it is in conventional methods. The backing molding material is the preparatory material that is molded to make the backing material. The backing molding material is obtained in the winding step by cutting the paper sheet into a tape-like form and winding it into a ring shape. As a result, the yield of the material used to make the backing is improved.

[0011] A manufacturing method for a backing molding material for a two-layered facing in accordance with a second aspect of the present invention is the method of the first aspect, wherein the papermaking step manufactures the paper sheet such that the basis weight thereof is greater than or equal to 0.025 kg/m² and less than or equal to 0.110 kg/m².

[0012] By making the basis weight less than or equal to 0.110 kg/m² in the paper making step, excellent winding of the paper sheet can be accomplished in the winding step. Also, by making the basis weight greater than or equal to 0.025 kg/m², it is easier to peel the sheet of fiber substrate, which contains short fibers and pulp, from a paper making screen. Note that the basis weight is the weight per one square meter of the paper sheet.

[0013] A manufacturing method for a facing having a two-layered structure in accordance with a third aspect of the present invention includes the following steps:

[0014] A front material preparation step in which the front material is prepared

[0015] A manufacturing step for a backing molding material in accordance with the first or second aspect; and

[0016] A molding step in which the backing molding material and the front material are laminated together and molded to obtain a facing having a two-layered structure.

[0017] With this manufacturing method, an inexpensive two-layered facing is obtained because the two-layered facing is manufactured using a backing molding material whose material yield has been improved.

[0018] These and other objects, features, aspects, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Referring now to the attached drawings which form a part of this original disclosure:

[0020]FIG. 1 is a schematic perspective view of a two-layered facing in accordance with a preferred embodiment of the present invention;

[0021]FIG. 2 is an elevational view of a backing molding material of the two-layered facing;

[0022]FIG. 3 is a cross-sectional view of the backing molding material of the two-layered facing taken along line A-A of FIG. 2;

[0023]FIG. 4 is a diagrammatical view of a manufacturing process in accordance with a preferred embodiment of the present invention for the two-layered facing;

[0024]FIG. 5 is a cross-sectional view of the two-layered facing illustrating a layered condition of the front material and backing material before the molding step; and

[0025]FIG. 6 is a cross-sectional view of the two-layered facing illustrating the layered condition of the front material and backing material after the molding step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A selected embodiment of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following description of the embodiment of the present invention is provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0027] (1) Constituent Features of Two-layered Facing

[0028]FIG. 1 illustrates a two-layered facing 1 in accordance with a preferred embodiment of the present invention. The two-layered facing 1 is preferably mounted to an outer circumferential portion of a clutch disc (not shown) and serves to engage frictionally with a flywheel (not shown) by being pressed thereagainst. The two-layered facing 1 is preferably a circular ring-shaped member having a front material 2 and a backing material 3. The front material 2 is pressed directly against the flywheel. The backing material 3 is fixed to a back surface of the front material 2 and serves as a strengthening member.

[0029] The front material 2 is preferably made of a rubber substrate impregnated with a friction adjusting agent and a thermosetting resin. Rubbers such as nitrile butadiene rubber (NBR), a synthetic rubber formed by polymerization of acrylonitrile and butadiene, and styrene butadiene rubber (SBR), a synthetic rubber formed by polymerization of butadiene and styrene, are used as the rubber of the substrate. Powders of such inorganic substances as calcium carbonate, magnesium carbonate, barium sulfate, and silica and such organic substances as cashew dust and rubber dust are preferably used as the friction adjusting agent. The thermosetting resin is preferably a phenol-based thermosetting resin, e.g., a resol, novolak, or denatured phenol resin. In this embodiment, a resol type phenol resin is used.

[0030] Referring to FIGS. 2 and 3, the backing material 3 is manufactured when a backing molding material 5 is molded integrally to the front material 2. The backing molding material 5 is made of a paper sheet 4 that has been cut into a tape-like form and wound into a ring shape. The paper sheet 4 is a very thin sheet obtained by blending short fibers and pulp, making the paper sheet 4 into a sheet of fiber substrate using a papermaking technique, and coating the sheet with a binding agent. It is preferable that the short fibers contained in the paper sheet 4 be glass fibers or aramid fibers. Fibers having a fiber diameter greater than or equal to 6 μm and less than or equal to 13 μm, and having a fiber length greater than or equal to 3 mm and less than or equal to 24 mm are often used. The basis weight of the paper sheet 4 is greater than or equal to 0.025 kg/m² and less than or equal to 0.110 kg/m².

[0031] The pulp contained in the paper sheet 4 includes natural fibers, synthetic fibers, or a blend of a plurality of these. Examples of natural fibers used include wood fibers and leaf fibers and examples of synthetic fibers include aramid and polyester. The binding agent contained in the paper sheet 4 is preferably a phenol-based thermosetting resin, e.g., a resol, novolak, or denatured phenol resin.

[0032] (2) Manufacturing Method for Two-layered Facing

[0033] Next, the method of manufacturing two-layered facing 1 is described.

[0034]FIG. 4 shows a manufacturing process for two-layered facing 1 in accordance with a preferred embodiment of the present invention. This manufacturing process includes the following steps: a front material preparation step 11 in which the front material is prepared; a backing material preparation step 21 in which the backing molding material 5 is prepared; and a molding step 31 in which the two materials are laminated together and molded to obtain a two-layered facing 1.

[0035] First, in the front material preparation step 11, a glass roving substrate impregnated with rubber, a friction adjusting agent, and a thermosetting resin is dried and rolled to manufacture the surface material 2. The backing molding material 5 is manufactured in the backing preparation step 21, which is separate from the preparation of the front material 2.

[0036] The backing material preparation step 21 includes the following steps: a papermaking step 22 in which short fibers and pulp material are blended and made into a paper. The paper is then coated with a binding agent and dried to obtain a paper sheet 4; and a winding step 23 in which the paper sheet 4 is cut into a tape-like form and rolled into a ring shape to obtain the backing molding material 5.

[0037] In the papermaking step 22, the paper sheet 4 is made basically according to the following steps using short fibers and pulp as raw materials.

[0038] {circle over (1)} Raw Material Step

[0039] Short fibers and pulp are dispersed in water and blended to make a slurry. The slurry is adjusted to a concentration appropriate for wet papermaking and sent to a wet papermaking step.

[0040] {circle over (2)} Wet Papermaking Step

[0041] The concentration-adjusted slurry is directed to a papermaking machine and a sheet of fiber substrate containing short fibers and pulp is made on a papermaking screen provided in the papermaking machine. The sheet is then “dewatered” in a vacuum extractor, peeled off the screen, and sent to the coating step.

[0042] {circle over (3)} Binding Agent Deposition Step

[0043] A binding agent made of a powdered thermosetting resin is sprayed onto the dewatered fiber substrate sheet, which contains short fibers and pulp.

[0044] {circle over (4)} Drying Step

[0045] After the binding agent is deposited on the fiber substrate sheet, which contains short fibers and pulp, the sheet is rough dried in an oven dryer. Then the sheet is dried further with a surface dryer and the paper sheet 4 is obtained.

[0046] {circle over (5)} Inspection Step

[0047] Before being sent to the winding step 23, the paper sheet 4 is inspected for defects and proper basis weight.

[0048] If the basis weight is below 0.025 kg/m², the fiber substrate sheet containing short fibers and pulp might not have peeled properly from the papermaking screen in the wet papermaking step, causing defects in the paper sheet 4. Therefore, the basis weight is inspected to make sure it is greater than or equal to 0.025 kg/m². Meanwhile, if the basis weight is larger than 0.110 kg/m², the sheet might not wind properly in the subsequent winding step 23. Therefore, the basis weight is inspected to make sure it is less than or equal to 0.110 kg/m². If the basis weight is outside the aforementioned range of values at the inspection step, the slurry concentration is readjusted at the raw material step.

[0049] In the winding step 23, the paper sheet 4 obtained in the papermaking step 22 is cut into a tape-like form using a slitter machine. The tape-like paper sheet 4 is then wound to the size of a prescribed backing material 3 on a winding machine and becomes the backing molding material 5, as shown in FIG. 3. In short, as seen in FIGS. 1 and 3, the thickness of the backing material 3 is adjusted by the width of the cut tape made from the paper sheet 4 and the diameter of the same is adjusted by the number of windings of the tape. The width of the tape is such that when the tape is compressed in the molding step 31 (discussed later), it becomes the prescribed thickness of the backing material 3.

[0050] Next, as shown in FIGS. 5 and 6, the front material 2 manufactured in the front material preparation step 11 and the backing molding material 5 manufactured in the backing material preparation step 21 are laminated together and molded integrally into a two-layered facing 1 by applying pressure in the direction of arrow X using a thermoforming press. The backing molding material 5 is compressed in the direction of arrow X until it is the prescribed thickness of the backing material 3.

[0051] The manufacturing method for a two-layered facing described here achieves a better yield from the material used to make the backing material 3 than conventional methods because the backing molding material 5, which is the preparatory material that is molded to make the backing material 3, is manufactured in the backing material preparation step 21 (which is provided with the winding step 23). Thus, an inexpensive two-layered facing is obtained because the two-layered facing is manufactured using a backing molding material 5 whose material yield has been improved.

[0052] The two-layered facing of the present invention does not waste backing material in a conventional manner because the backing molding material, which is a preparatory material molded to make the backing material, is obtained by cutting a paper sheet into a tape-like form and winding it into a ring shape. Consequently, the yield of the material used to make the backing material is improved and an inexpensive two-layered facing is obtained.

[0053] As used herein, the following directional terms “forward, rearward, above, downward, vertical, horizontal, below and transverse” as well as any other similar directional terms refer to those directions of a device equipped with the present invention. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a device equipped with the present invention.

[0054] The terms of degree such as “substantially,” “about,” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.

[0055] This application claims priority to Japanese Patent Application No. 2001-231026. The entire disclosure of Japanese Patent Application No. 2001-231026 is hereby incorporated herein by reference.

[0056] While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing description of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 

What is claimed is:
 1. A manufacturing method for a backing molding material that is molded integrally with a front material having a friction surface in a two-layered facing, comprising: a papermaking step being configured to obtain a paper sheet by blending short fibers and pulp material and making said short fibers and pulp material into paper, coating said paper with a binding agent, and drying said paper; and a winding step being configured to obtain a backing molding material by cutting said paper sheet into a tape-like form and winding it into a ring shape.
 2. The manufacturing method for a backing molding material for a two-layered facing as recited in claim 1, wherein said papermaking step manufactures said paper sheet such that the basis weight thereof is greater than or equal to 0.025 kg/m² and less than or equal to 0.110 kg/m².
 3. A manufacturing method for a two-layered facing, comprising: a front material preparation step being configured to prepare a front material; a manufacturing step being configured to manufacture a backing molding material, said manufacturing step comprising, a papermaking step being configured to obtain a paper sheet by blending short fibers and pulp material and making said short fibers and pulp material into paper, coating said paper with a binding agent, and drying said paper, and a winding step being configured to obtain a backing molding material by cutting said paper sheet into a tape-like form and winding it into a ring shape; and a molding step being configured to laminate said backing molding material and said front material together and to mold to obtain a facing having a two-layered structure.
 4. The manufacturing method as recited in claim 3, wherein said papermaking step manufactures said paper sheet such that the basis weight thereof is greater than or equal to 0.025 kg/m² and less than or equal to 0.110 kg/m².
 5. The manufacturing method as recited in claim 4, wherein said front material is made of a rubber substrate impregnated with a friction adjusting agent and a first thermosetting resin.
 6. The manufacturing method as recited in claim 5, wherein said binding agent is made of a second thermosetting resin.
 7. The manufacturing method as recited in claim 6, wherein a rubber of said rubber substrate is selected from the group consisting of NBR and SBR.
 8. The manufacturing method as recited in claim 7, wherein said friction adjusting agent is selected from the group consisting of calcium carbonate, magnesium carbonate, barium sulfate, silica, cashew dust, and rubber dust.
 9. The manufacturing method as recited in claim 8, wherein said thermosetting resin is phenol based.
 10. The manufacturing method as recited in claim 9, wherein said first and second thermosetting resins are selected from the group consisting of resol, novolak, and denatured phenol resin.
 11. The manufacturing method as recited in claim 4, wherein said short fibers are glass or aramid fibers.
 12. The manufacturing method as recited in claim 11, wherein said short fibers have a fiber diameter greater than or equal to 6 μm and less than or equal to 13 μm.
 13. The manufacturing method as recited in claim 12, wherein said short fibers have a fiber length greater than or equal to 3 mm and less than or equal to 24 mm.
 14. The manufacturing method as recited in claim 13, wherein said pulp comprises natural and/or synthetic fibers.
 15. The manufacturing method as recited in claim 14, wherein said natural fibers are selected from the group consisting of wood fibers and leaf fibers, and said synthetic fibers are selected from the group consisting of aramid and polyester.
 16. The manufacturing method as recited in claim 4, wherein said papermaking step comprises, a raw material step in which said short fibers and pulp material are dispersed in liquid and blended to make a slurry, a wet papermaking step in which said slurry is directed to a papermaking machine that produces a sheet of fiber substrate on a screen said sheet of fiber substrate is dewatered, removed from said screen, a binding agent deposition step in which said binding agent is sprayed onto said sheet of fiber substrate, said binding agent comprising powdered thermosetting resin, a drying step in which said sheet of fiber substrate is dried, and an inspection step in which said sheet of fiber substrate is inspected prior to said winding step.
 17. The manufacturing method as recited in claim 16, wherein said molding step further comprises compressing a width of said backing molding material to adhere to a predetermined thickness.
 18. The manufacturing method as recited in claim 3, wherein said short fibers are glass or aramid fibers.
 19. The manufacturing method as recited in claim 18, wherein said short fibers have a fiber diameter greater than or equal to 6 μm and less than or equal to 13 μm, and said short fibers have a fiber length greater than or equal to 3 mm and less than or equal to 24 mm.
 20. The manufacturing method as recited in claim 19, wherein said pulp comprises natural and/or synthetic fibers, said natural fibers are selected from the group consisting of wood fibers and leaf fibers, and said synthetic fibers are selected from the group consisting of aramid and polyester. 